Inch by inch, hybrids and electric cars are gaining ground in the U.S. auto market.

Automakers sold 54,855 hybrids in August, reports Autodata Corp., a sales tracking firm. That is a 32% gain from the same month a year earlier and an industry record for any prior month.

Sales of rechargeable cars, which include plug-in hybrids such as the Chevrolet Volt and electric-only vehicles such as the Tesla Model S and Nissan Leaf, also set a record last month, climbing to 11,392, a 147% gain from the same period a year ago.

Together, hybrids and electric cars accounted for about 4% of U.S. auto sales last month.

Several factors are behind that growth.

Ford has joined Toyota as a big seller of hybrids. The head-to-head competition between the two automakers is catching the attention of consumers.

Expect the market to take another leap when the hybrid version of the Honda Accord – which is rated at 50 miles per gallon in city driving – reaches showrooms in the coming months.

The gasoline version of the vehicle has a huge following that has made the Accord one of the best-selling passenger cars in America.

“It's safe to say that we expect the Accord Hybrid to be the best-selling hybrid in our lineup in the near future,” said Honda spokesman Chris Martin.

The Tesla Model S is another contributor. Tesla Motors is selling almost 2,000 of the expensive luxury electric cars a month after slowly ramping up production and sales last year and into this year.

Price cuts for electric cars such as the Leaf and plug-ins such as the Volt also have stimulated sales.

The average transaction price for a Nissan Leaf has fallen by almost $5,000 to $30,970 over the past year, according to auto price information company Kelley Blue Book. The average price of the plug-in version of the Toyota Prius has dipped more than $1,000 to $32,564 over the same time period.